types: convert to new charset before inserting to blob or json column

[tangenta]

What problem does this PR solve?

Issue Number: close #30690

Problem Summary:

set names gbk;
drop table if exists t;
create table t (b blob, d json);
insert into t values ('你好', '{"测试": "你好"}');
select * from t;

The expected insertion procedure for TiDB is:

1. '你好' is parsed with GBK(because of the@@character_set_client), resulting a UTF-8 string '浣犲ソ' datum annotated with "gbk_bin"(because of the @@character_set_connection).
2. Before inserting to a binary type like blob and json, another conversion from UTF-8 to GBK is needed. Thus '浣犲ソ' should be changed back to '你好'.

Previously, step 2 is missed for type blob and json, this PR fix the issue.

What is changed and how it works?

This PR also moves string encoding/decoding/validation to Datum.ConvertTo().

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

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• Defined2014
• xiongjiwei

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[dianqihanwangzi]

/run-check_dev_2

[Defined2014]

It's not same as MySQL.

[tangenta]

I think it is OK to have this difference?

[Defined2014]

Em... Not sure. Seems we had a PR to fix it before. #25087

[tangenta]

This PR does not introduce the garbled code as described in #25087. It extracts the error message from ErrInvalidCharacterSet(which should be in a well format).

The only difference is the number of invalid bytes displayed.

[tangenta]

testColumnTypeChangeSuite.TestChangeFromBitToStringInvalidUtf8ErrMsg is failed but I try it on MySQL 5.7.36 and 8.0.27. The result is different from the test:

mysql> create table t (a bit(45));
Query OK, 0 rows affected (0.02 sec)

mysql> insert into t values (117471723421);
Query OK, 1 row affected (0.01 sec)

mysql> alter table t modify column a varchar(31) collate utf8mb4_general_ci;
Query OK, 1 row affected (0.05 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from t;
+--------------+
| a            |
+--------------+
| 117471723421 |
+--------------+
1 row in set (0.03 sec)

We can see that even if non-binary string, the bit type is changed to int first instead of varchar directly. This is conflict with #25037 (comment):

2: when cast the bit to binary, we should consider to convert it to uint then cast uint to string, rather than takeing the bit to string directly.

[tangenta]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 0c00650

[tangenta]

/run-unit-test

[2021-12-30T07:50:53.565Z] FAIL: client_test.go:104: testRestoreClientSuite.TestIsOnline
[2021-12-30T07:50:53.565Z] 
[2021-12-30T07:50:53.565Z] client_test.go:105:
[2021-12-30T07:50:53.565Z]     c.Assert(s.mock.Start(), IsNil)
[2021-12-30T07:50:53.565Z] ... value *errors.withStack = listen tcp 0.0.0.0:41402: bind: address already in use ("listen tcp 0.0.0.0:41402: bind: address already in use")

[zimulala]

/run-unit-test

[2021-12-30T08:38:41.665Z] FAIL: db_test.go:40: testRestoreSchemaSuite.SetUpSuite
[2021-12-30T08:38:41.665Z] 
[2021-12-30T08:38:41.665Z] db_test.go:47:
[2021-12-30T08:38:41.665Z]     c.Assert(s.mock.Start(), IsNil)
[2021-12-30T08:38:41.665Z] ... value *errors.withStack = listen tcp 0.0.0.0:36262: bind: address already in use ("listen tcp 0.0.0.0:36262: bind: address already in use")
[2021-12-30T08:38:41.665Z] 

[tangenta]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d96bcde

[ti-chi-bot]

@tangenta: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[tangenta]

/run-unit-test because it is timeout.
/run-check_dev_2 because a goroutine is leak.

[tangenta]

/run-unit-test